1. Field of the Invention
The present invention refers to an apparatus for the non-destructive testing of the integrity and/or suitability of sealed packagings, preferably food packagings, in particular through a verification of conformity of the atmosphere inside such food packagings.
2. Description of Related Art
Regarding the preservation of food products there is known the packaging in modified atmosphere, i.e. in sealed packagings filled with a determined gas or mixture of gases capable of preserving the food products therein, maintaining the organoleptic properties thereof substantially unaltered. Such packagings are known by the MAP (Modified Atmosphere Packaging) acronym.
In particular, regarding the correct preservation of food, the content of oxygen present in the packaging is of great importance. Specifically, regarding each food product, the correct preservation is obtained by means of a characteristic concentration of oxygen.
Generally there is the tendency of reducing the amount of oxygen with respect to the one present naturally in the atmosphere, for example replacing it with carbon dioxide or nitrogen, as the degradation of food is mainly due to the presence of oxygen in the packaging which causes the oxidation of various proteins widely present in most food products.
An exception is however represented by meat, especially minced or sausages, in which in order to heighten the red colour, there is introduced a higher amount of oxygen with respect to that present in the atmosphere. Therefore, there definitely arises the need of being able to monitor the concentration of gases inside the packagings, in particular of the food product type, with the aim of verifying the maintenance of the nominal characteristics.
Thus, besides identifying food packagings with mixtures of gases not meeting the desired standards, for example due to incorrect filling thereof, it is also possible to identify packagings not sealed correctly, thus in which the mixture of gases is similar to that of the external atmosphere.
Currently it is known to verify the concentration of a gas inside a sealed food packaging by collecting—using a syringe—a sample of the mixture of gases inside such container and analysing it with a suitable sensor of the contact type such as an electro-chemical sensor or the like, such as for example a lambda probe. Such measurements, though providing reliable results, reveal considerable drawbacks of use due to the complexity and the times required for performing the test, as well as the fact that, in order to collect the sample of the mixture of gases inside a sealed packaging, such packaging is irremediably jeopardised thus not being suitable for re-introduction into the production line.
This makes such measurements suitable for solely sample testing, thus definitely excluding the possibility of their use in line with the aim of performing a test on the entirety of the produced packagings.
Furthermore, there is known a system for non-destructive testing of the integrity and suitability of sealed food packagings described in the International patent application WO 2010/145892.
Such system measures, through laser spectroscopy, the radiation portion of the diffusive type which exits from a food packaging, after sending a laser radiation thereinto.
According to such measurement there is determined the absorption of the radiation operated by a determined gas present in the packaging which, compared with an expected absorption value, provides an indication in relation with a possible alteration of the concentration of such gas.
Thus, the system described in WO 2010/145892 is not capable of providing an absolute measurement of the concentration of the measured gas, thus leading to the need of providing a specific reference for each type of packaging and food product contained therein.
Furthermore, there is known another laser spectroscopy system used in particular for the non-destructive testing of the integrity and suitability of sealed food packagings filled with liquids where it is assumed that the water vapour is in saturation and the value thereof is thus a function of the temperature alone.
Such system provides alongside the measurement of the gas intended to be monitored a second measurement channel based on the measurement of the water vapour. Thus, such second measurement channel provides a reference from which the absolute measurement of the gas to be monitored is derived.
It is clear that the need for a second measurement channel makes the apparatus complex and expensive. Furthermore, such known apparatus cannot be used in packagings containing solid food products.